RE: 20 guage too small
A .44 magnum and a 410 shotgun slug are very similar ballisticaly, but for some reason people are very impressed the the .44 and not so impressed with the 410. Maybe Dirty Harry had something to do with it. Anyway, another fact is that buck shot is very limited in power and accuracy. Go ahead and fire back at me, but do your research first. Having studied buck shot, I would never take it hunting, unless slugs were not allowed.
That said, if I had a twenty and wanted to go deer hunting, I'd load it up with slugs. No reason in the world not to. If slugs were not allowed, I think I'd have to go buy a 12 or even a 10ga.
Not really realated, but just thought you may want to know. I just bought my son his first shot gun. It is a twenty ga. 870. It is what he requested for X-mas.
Good luck.